Speeds at the newly resurfaced Michigan International Speedway are very close to dangerous, one Sprint Cup driver said during Thursday's test. "We're approaching some safety concerns at the speeds we are going," said Greg Biffle, after speeds reached 218 mph during the morning session. "We've got to walk that fine line of killing people and creating excitement." Read more: http://espn.go.com/racing/nascar/cup/story/_/id/8052308/speeds-reach-218-mph-michigan-test-session
